1. Field of the Invention
The present invention relates to liquid pumps and, more particularly, to a system for preventing damage to a pump that would otherwise occur by running the pump without an adequate liquid supply.
2. Prior Art
U.S. Pat. No. 3,885,739 to Tuttle discloses a pressure fluid cleaning device with a dump valve that is closed by activation of a trigger. U.S. Pat. No. 2,969,740 to Kaatz discloses a sump pump with a pressure switch adapted to deactivate the pump in the absence of liquid. U.S. Pat. No. 2,741,988 to Merritt discloses a system adapted to shut off power to a motor of a pump in the event the pump should lose its prime. U.S. Pat. No. 3,104,614 to Gramenzi discloses a control device Other U.S. Patents relating to pumps include 2,687,693; 2,804,516; 2,910,003; 3,794,789; 4,861,231; and 5,064,347.
As noted from the above cited references, it is generally not desirable to operate a liquid pump without the presence of a liquid at its inlet because the pump could become damaged. There also exists in the prior art systems known as pressure washers that comprise a motor driven liquid pump and a wand such as disclosed in U.S. Pat. No. 5,086,975. As noted in U.S. Pat. No. 5,086,975, liquid is supplied to the pump by a hose. Problems have arisen in regard to supplying liquid to pumps by means of disconnectable hoses, such as garden hoses. First, the hose is usually connected to the pump prior to supplying liquid to the hose. Air, trapped in the hose, is thus pushed into the pump causing the pump to operate without the proper presence of liquid. Second, occasionally, a water supply to the pump is interrupted (or the pump is started without being properly connected to the water supply), such as when the hose becomes kinked, etc. This causes a loss of supply of water to the pump. Operating the pump without an adequate supply of water can thus result in damage to the pump.
It is an object of the present invention to overcome problems in the prior art and provide a new and improved system for protecting a liquid pump from damage from inadequate liquid supply.